Berlin 2015 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 21: Superconductivity: Poster Session

TT 21.54: Poster

Monday, March 16, 2015, 15:00–18:00, Poster B

Development of RF-SETs for error detection in semiconductor electron pumps — •David Reifert, Niels Ubbelohde, Ralf Dolata, Lukas Fricke, Thomas Weimann, and Alexander Zorin — Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig. Germany

Semiconductor single electron pumps allow the transport of single electrons with a frequency f (about 1 GHz) which results in a current (I=e*f) in the range of about 0.1 nA. However, since the accuracy of these pumps (at present still worse than 1 ppm) is not sufficient for metrological applications, we developed a method to detect and account the errors of these pumps, which should lead to an improved accuracy. To realise this error detection we put several electron pumps in a serial circuit with intermediate charge islands between them. If one of the pumps operating simultaneously makes an error the charge on the island changes stepwise which can be detected by a sensitive charge detector. We use superconducting Al single electron transistors (SETs) as ultra-sensitive charge detectors which are capacitively coupled to the intermediate charge islands. In our previous experiments we operated the SETs in DC mode which allowed rather slow measurement bandwidth of a few kHz. To increase the measurement bandwidth of the SETs we put them in a resonant tank circuits and measure the reflectance of these resonators at corresponding frequencies. This tank circuit matches the high impedance of the SET (>100 kOhm) to a 50 Ohm line. We will show the general measurement setup and some first measurements of charge detection with such a RF-SET.